Muscular system Flashcards
Explain the location, function and description of skeletal muscle.
- Location= Attached to bone
- Function= Voluntary movement
- Description= Striated, multinucleate (more than one nucleus)
Explain the location, function and description of cardiac muscle.
- Location= Walls of the heart
- Function= In-voluntary control, auto-rhythmic
- Description= Striated, uninucleate cells interlock at intercalated discs, single nucleus
Explain the location, function and description of smooth muscles.
- Location= Walls of hollow organs
- Function= Involuntary, auto rhythmic, propels substances along internal passageways.
- Description= non-striated, cells arrange in a sheet structure, single nucleated
What are the functions of muscle?
- Movement
- Posture
- Regulating organ volume
- Moving substances in the body= Cardiac muscle (heart), smooth muscle (peristalsis), skeletal muscle (lymph / blood)
- Heat production
What are the different characteristics of muscle?
- Excitability= ability to respond to a stimulus
- Contractability= ability to contract when stimulated
- Extensibility= ability to be stretched/ extended
- Elasticity= ability to return to its original form after being stretched
When does movement occur?
- When a muscle contract.
- Movement results from several muscles working together
- Most skeletal muscles are arranged in opposing pairs
= Antagonistic Pairs
Muscles are arranged in opposing pairs, what are these called?
- Antagonistic pairs.
- Agonist= contracts to cause an action
- Antagonist= stretches and yields to action of the agonist
- Synergist= contracts to stabilise intermediate joints
- Fixator= stabilises origin of agonist
What are muscle made up of?
- Bundles of muscle fibres called fascicles. These muscles and fibres are held together by sheets of connective tissue.
What are the sheets of connective tissue found in muscle?
- Epimysium= surrounds whole muscle
- Perimysium= surrounds bundles of fibres (fascicles).
- Endomysium= surrounds individual muscle fibres
What are the different contractile proteins?
- Actin and myosin are the contractile proteins.
- Troponin and tropomyosin are contraction inhibiting proteins.
What is ATP?
- Produces energy for muscles.
- It is produced through different metabolic pathways: Creatine phosphate, anaerobic respiration and aerobic respiration.
What does anaerobic respiration do?
- Provides ATP for short, moderate durations of activity (60 secs or slightly more). It does not require O2 and has two stages: Glycolysis and lactic acid formation.
- So, breakdown of glucose into pyruvic acid (through glycolysis). It produces 2 ATP molecules per breakdown of glucose molecule. Pyruvate is then converted to lactic acid in absence of O2.
What does creatine phosphate do?
- Provides ATP for first few seconds of high intensity activity.
- Creatine phosphate donates a phosphate group to ADP from ATP, it is catalysed by the enzyme creatine.
- The reaction= creatine phosphate + ADP= creatine + ATP
What does aerobic respiration do?
- Provides ATP for prolonged activities: several mins- hours.
- It requires O2 and has three stages: glycolysis, kreb’s cycle, oxidative phosphorylation.
- Mechanism: Involves Krebs cycle, oxidation of glucose, fatty acids and amino acids in presence of oxygen. Produces 32 ATP molecules per glucose molecule.
What are some physiological changes during exercise?
- Increase in CO2 and lactic acid
- Increase in muscle movement
- Increase return of blood flow to the heart
What receptors detect physiological changes?
- Chemoreceptors detect co2
- Proprioceptors detect muscle movement
- Baroreceptors detect blood flow to the heart
What are the outcomes of these physiological changes?
- Increase ventilation and cardiac output
- Vasodilation, vasoconstriction and increased sweating etc.
What changes do skeletal muscles go through as we age?
- Sarcopenia= loss of muscle mass and strength.
- Reduced muscle repair and regeneration
- Neuromuscular changes and motor neuron loss
- Increased muscle stiffness
What are muscle fibres made up of?
= Myofibrils.
Myofibrils are divided lengthways into sarcomeres, which have the myofilaments actin and myosin.
What happens during muscle attachment?
- One end of the muscle is attached to a structure (usually bone) that remains stationary. This is known as the Origin of the muscle
- The opposite end of the muscle that is moved by the contraction is known as the Insertion
What are muscle fibres made up of?
- Myofibrils
- Each myofibril is made up of the contractile proteins Actin and Myosin to make Myofilaments.
- It is the overlapping of the thin actin and thick myosin filaments that give muscle its striated (striped) appearance
